There are many well known methods of changing or improving the flavor of brewed coffee or coffee extract. It has long been the goal of many such methods to improve coffee flavor without sacrificing the yield and convenience of conventional high temperature (i.e., temperature of aqueous extraction exceeding about 70.degree. C., 158.degree. F.) coffee extraction. Generally, high yield and high temperature extractions are convenient and economical but compromise coffee flavor. Consumers prefer the convenience of conventional brewing devices (i.e., percolators, electric percolators, drip coffee makers, automatic drip coffee makers), all of which use high temperature extraction. In the manufacture of soluble coffees, industry prefers the economics of high temperature, counter current extractions. Therefore, to be of any practical use to consumers or industry, methods of improving coffee flavor must also produce an acceptable extraction yield without sacrificing the convenience and economic benefit associated with high temperature coffee extraction.
Selective extraction is one general approach to improving the flavor of brewed coffee or coffee extract. According to this approach, a preferred ratio of bad to good coffee flavors are extracted from roast ground coffee. Ideally, this selective extraction improves the overall flavor of brewed coffees or coffee extracts without compromising its flavor strength or extraction yield.
Two well known selective extraction methods are low temperature extraction and selective extraction via adsorbents. Although both methods are known to improve coffee flavor, it is also known that each method has serious deficiencies.
It has long been known that low temperature extraction of roast ground coffee produces a brewed coffee or coffee extract having an improved flavor. As early as 1880, U.S. Pat. No. 228,889 to Gue et al. disclosed a low temperature extraction of coffee. Likewise, U.S. Pat. No. 3,700,466 to Bergeron et al., issued Oct. 24, 1972, discloses the advantages of low temperature aqueous extraction of roast ground coffee. These low temperature extractions, whether brewed coffee or coffee extract, have a preferred flavor relative to conventional high temperature extractions. For example, toddy coffee (low temperature brewed coffee) has been described as mild and aromatic with a sweet, caramel-like taste. The preferred flavor character of toddy coffee is based on relatively high levels of certain desirable coffee flavor components. These desirable components include aldehydes, diketones, pyrazines, and caramel compounds such as furaneol. The preferred flavor character of toddy coffee is also due to a much lower level of certain undesirable coffee flavor components. These undesirable flavor components include the guaiacols, as well as other phenolic compounds.
Low temperature extraction, whether by counter current methods of making soluble coffee or by brewing toddy coffee, therefore, selectively removes more good flavor components relative to bad flavor components. However, these low temperature extractions sacrifice yield for improved flavor. For example, extraction yield for toddy coffee is about 15% while conventional high temperature brewing produces about a 20-30% yield. Counter current high temperature extraction in the manufacture of soluble coffees produces about a 50-60% yield while low temperature counter current extraction yields considerably less. It would be desirable to have the preferred flavor of low temperature extracts but with the yield of conventional high temperature extraction.
Also well known is the use of adsorbents in coffee to improve the flavor of brewed coffee or coffee extract. Unlike low temperature extraction, adsorbents accommodate high temperature conditions and also preferably adsorb a favorable ratio of bad flavor components to good flavor components without sacrificing yield and convenience. Adsorbents used in roast ground coffee include activated carbons (i.e., activated charcoals), carbohydrates and carbohydrate polymers (i.e., alginic acid), synthetic polyamides (i.e., insoluble polyvinylpyrrol idone), certain mineral substances (i.e. aluminum oxides, silica gel), and proteinaceous materials (i.e., chitosan, chitan).
These prior art adsorbents have been used in various ways to improve the flavor of brewed coffee or coffee extracts. Some have been added to extraction columns in industry, to the extract from extraction columns, to packaged roast ground coffee marketed for consumer use, or to the structure of coffee filters used in conventional brewing devices. These adsorbents improve the flavor of brewed coffee or coffee extract by either adsorbing (and therefore removing) a favorable ratio of bad flavor components to good flavor components, or by adsorbing good flavor components during storage and releasing them upon extraction.
The prior art discloses various ways of using adsorbents to improve coffee aroma and flavor. Japanese Patent Application 59179034, published Oct. 11, 1984, discloses the use of amino-polysaccharide adsorbents to remove mutagenic substances from brewed coffee by incorporating the adsorbents in the fabric of, or placed between, coffee filters. EAST German Patent Application 268151, Published May 24, 1989, discloses the use of silica gel and zeolites as adsorbents added directly to packaged roast ground coffee so as to stabilize and retain coffee aroma and flavor. U.S. Pat. No. 1,930,257 to Stelkens, issued Oct. 10, 1933, also discloses adsorbents added directly to packaged roast ground coffee, the adsorbent being activated charcoals. U.S. Pat. No. 3,625,703 to Ericson, issued Dec. 7, 1971, discloses a roast ground coffee with dried vegetable matter that produces a brewed coffee having less oil and acid.
Historically, adsorbents added to coffee products have had limited success. Besides being expensive, adsorbents frequently adulterate the coffee beverage (i.e., adsorbent particles pass into the coffee beverage) and add an undesirable flavor or texture to the coffee.
It is therefore an object of this invention to provide a coffee composition that results in brewed coffee or coffee extract with reduced burnt aromas and reduced bitter flavors.
It is a further object of this invention to provide an adsorbent that is inexpensive, unadulterating, tasteless, and selective for bad coffee flavor notes.
These and other objects of this invention will become obvious from the description herein.